Cam sprocket alignment (two less spacers)

[3literpwr]

Finally getting to installing the cams in my 3.0 SC rally motor and noticed something strange when checking alignment. My car had four spacers both left and right when it was taken apart. I have no idea if the motor was gone through or messed with, but it did have Carrera tensioners added at some point... So...I went to check the spacing and both sides were rather out when installed with the 4/4 shims as originally removed.

In the end I got the spacing in spec with the left measuring at 54.89 with three spacers and the right at 0.03 with two spacers. I have read on a few pages and in Waynes book that four is the norm. Should I be concerned that I now have 2? Where did that extra 1mm come from? The the surfaces were cleaned with a stone and the cam towers are stock. The jugs where replated by EBS, but I can't say they are in the same bore as before. Cams are now DC60, but that shouldn't matter.

Thanks

[boyt911sc]

Are we talking about the cam sprockets alignment? Those numbers seemed to be odd!!!! Could you post some pictures just to be sure we are on the same page? Thanks.

Tony

[3literpwr]

Yup cam sprockets....

[Gordo2]

I went through something similar with my rebuild - but I had new cams.

In the end, after loads of research I decided that as long as you are reasonably confident in your measurements, the # of spacers you end up with to get there is fine (assuming you don't have something way outside the norm).

Good luck,

Gordo

[boyt911sc]

I got your PM. Those measurements were very good and well within spec. You are ready to go for the next stage.......cam timing.

Tony

[3literpwr]

FYI... I also am using NEW DC60 cams. I plan to get another straight edge to be safe and double check measurements tonight.

Thanks for the help!

[Gordo2]

Originally Posted by 3literpwr

FYI... I also am using NEW DC60 cams. I plan to get another straight edge to be safe and double check measurements tonight.

Thanks for the help!

Sorry, BTDT too...

I guess I should have also mentioned not only did I research boatloads - I also measured at least 30 or more times and bought a decent straight edge midway through.

Bottom line - you're doing fine.

Gordo

[KTL]

The sprocket parallelism thing is certainly a proper way to ensure best operation of the chains and sprockets. However if they're not perfectly parallel? The engine isn't doomed to destroy itself. You'll just end up with some side-wear on the sprockets.

I'm certainly not endorsing that the sprocket alignment should be treated carelessly. Just saying that it's not a catastrophe if the alignment isn't spot-on. Reason I mention this is because I actually found the 4-5-6 right side sprocket installed backwards on one of my engines when doing a top end service. That reversal of the sprocket confirmed to me that sprocket alignment is not super critical.

Nonetheless if something's worth doing, do it right. Just don't get too concerned about this one. If you're following the procedure properly and getting repeatable measurements, call it good and move on. It's entirely likely that the previous wrencher did it wrong/carelessly.

[cgarr]

How thick are the shims? That should tell you it will never be perfect, same with setting valve spring height.

[Kemo]

Originally Posted by cgarr

How thick are the shims? That should tell you it will never be perfect, same with setting valve spring height.

i had purchased new shims and they were thicker than the stock ones that I pulled off.

[Walt Fricke]

A mechanic once claimed that if you were off by two shims you could tell when rotating the motor with the covers off - things would jump around or otherwise just not look right pretty much no matter how experienced a guy was.

I still fuss around a lot. Buying the Stomski tool, however, allowed me to measure once and feel confident about it.

[3literpwr]

My shims are the standard .5mm thickness. The right side of my motor (originally had 4 shims and now has 2) did show wear on the outer side of the sprocket.

[Walt Fricke]

If 4 did that wear, 2 might well be much better.